"And I rarely have treats around that might tempt me late at night, which is when I usually crave something really fattening," she adds. "What am I going to do? Drive out at 11 at night just to satisfy a craving? No, that's crazy."

Boyfriend of seven months Jamie Kennedy, who costars with her on CBS' Ghost Whisperer, also helps.

"He's inspired me to improve my diet," she says. "He has a salad with every meal, plus lots of fruit, fish, and vegetables."

Every morning during a trip to Monaco last summer, "We ran for 40 minutes through the streets of Monte Carlo. It was an amazing way to see the city. Now when we travel, we try to explore the places by running."

Her other tip?

Ever since she turned 30 this past February, she gives herself positive affirmations.

"I fall asleep feeling beautiful," she says. "Then, in the morning, before I leave the house, I say five things I love about myself, like, 'You have really pretty eyes.' That way I can go out into the world with that little bit of extra confidence. It’s a feel-good protein shake in my back pocket in case someone messes with me that day."

Still, being confident 24/7 isn't always easy.

"I'm a girl, after all!" she says. "For the most part, yeah, I'm happy with my body, but there are days when I'm like, 'Ugh! Really? Why is it so hard to fit into my jeans?' That’s when I say to myself, 'I look this way because I'm supposed to. If we all looked the same, we'd be boring.'"